The present invention relates generally to large multiple serving beverage containers, in particular, beer kegs.
Metal beer kegs primarily made of stainless steel have been the preferred method of transporting draft beer from the brewery to the retailer (i.e. restaurant, bar, store) for many years. They come in several sizes, between a sixth barrel and a half barrel.
Metal kegs are very durable and can give many years of service. However, they have a high initial purchase price and several additional costs during use. First, shipping an empty keg back to the brewery increases the actual cost of using stainless steel or metal beer kegs. Next, the keg must be prepared for refilling, including being emptied, inspected, pressure checked, precleaned with water, cleaned with a caustic rinse, steam sterilized and evacuated with CO2 before it can be refilled. Damaged kegs must also be repaired as needed at this time.
The high cost of stainless steel has made it profitable for thieves to steal empty kegs and sell them for scrap. The cost of lost or stolen kegs further increases the cost of using metal beer kegs.
Most bottle or can beer is pasteurized, which is why it can be stored and sold at room temperature. The pasteurization also gives it a longer shelf life. Outside of the U.S., it is more common for keg beer to be pasteurized. In the U.S., most keg beer is not pasteurized. This means it must be kept cold from the time the keg is filled to the time it is emptied. Thus, there is another additional cost to the system to keep the keg beer refrigerated during transport and storage.
Beer spoils quickly once it is exposed to air. A keg that uses air for draft pressure will typically spoil within a few days. Commercial systems and the better home systems use CO2 as the preferred gas to pressurize the kegs and force the beer to flow. CO2 does not react with the beer and allows beer to remain fresh over several weeks.
Although draft beer is often available at restaurants and bars, however, it is difficult to sell draft beer for home consumption at a reasonable price. One obstacle to providing draft beer for the home market is the weight of a full keg of beer. A standard keg weighs approximately 160 pounds full and a pony keg (quarter barrel) weighs about 87 pounds full. Most stores also require an expensive deposit for the keg, which further inhibits the take-home market. The shape and size of kegs makes it difficult for the home user to refrigerate the keg without specialized coolers or refrigerators. Also, a typical home user does not have a CO2 system, which is required if the beer is to be consumed over longer than a weekend.
There are some proposed designs for one-way kegs. One design uses a combination of a PET bottle and a cardboard box with a valve/spear design. Another design uses a similar concept but replaces the valve/spear assembly with a bag. Neither design is all plastic.
One plastic one-way beer keg includes a blow-molded PET container (bottle), which contains the beer. A spear/valve assembly allows the keg to be filled and dispensed. A blow-molded outer container protects the bottle from damage and allows the package to be transported. A lid securely attaches to the valve and outer and inner containers to form a rigid package that protects the beer inside. The design looks like a traditional metal keg and works with existing equipment that interfaces with metal kegs. However, this design is still expensive, and much more expensive than returnable kegs. Further, the inner and outer shells act together as an insulation barrier. For pasteurized beer, which may be warm when purchased, this makes it much more difficult for the consumer to cool the beer. In addition, due to the shape of the liner and outer/inner shell combination, the beer volume is roughly half that of a similarly sized metal keg.